The present invention relates to devices such as intra aortic balloon pumps (IABPs) wherein an inflatable envelope or balloon mounted on the end of a long catheter is inserted through a blood vessel to a position in the aorta where it is operated to supplement the cardiac pumping action.
In a typical prior art construction, a manifold or handle is mounted to provide a separate fluid connection to each of an inner and an outer tube, which extend for a length of one to one and a half meters from the handle. At the far ends of the tubes a balloon is mounted to be inflated by the outer tube, while the inner tube extends through the balloon to provide a lumen for sampling fluids on the far (cardiac) side of the balloon. Commonly, the balloon is about the size and shape of a long hot dog, although other balloon designs are known.
Insertion of the balloon to a site in the aorta is accomplished by first compacting the uninflated balloon, by folding, wrapping, twisting or the like, and then inserting the compacted balloon assembly through an artery using a guide wire and/or sheath to guide it past irregularities or branches in the artery. Care must be taken during insertion to avoid trauma or perforation, particularly when the balloon is passing branches or curves of the artery.
Because the inflatable balloon is fabricated of a pre-shaped thin membrane of low intrinsic stiffness, it is customary to provide a support member within the balloon to hold the balloon extended in the longitudinal sense during pumping. This support member, which may simply be the end portion of the inner tube, or which may include a separate wire or wire-wrapped reinforcement, limits the ability of the balloon and to follow or conform to a curved arterial passage, and does not permit the balloon to remain stably positioned in a curved arterial section during pumping.